The pentalobe screw is a five-pointed screw designed by Apple for use in their products. It was first introduced in 2009 with its use in the 15-inch MacBook Pro, but has since expanded to be used in the iPod Classic, MacBook Pro, MacBook Air, and iPhone.
Visually, the Pentalobe screw appears to be a six-sided variant of the Torx standard. If you look more closely however, you will find that each point of the screw is rounded. This can also be seen in the name of the screw, which comes from its two parts. Penta is a prefix meaning five, and lobe which is defined by Merriam-Webster as “a curved or rounded projection or division”.
The pentalobe screw has been heavily criticized since its inception for seemingly being designed to lock users out of repairing their products by requiring non-standard screwdrivers. Though this has become less of an issue over time with the advent of inexpensive third party pentalobe screwdrivers from the likes of iFixit.